// Perform encoding.
const encodeContent = new TextEncoder().encode('hello world');
// Use crypto to perform SHA-256 hashing. The resulting hash is a promise that fulfills with an ArrayBuffer.
const sha256Content = await crypto.subtle.digest(
  { name: 'SHA-256' },
  encodeContent 
);
const result = new Uint8Array(sha256Content); 

// crypto.subtle
readonly subtle: SubtleCrypto;

crypto.getRandomValues(buffer: TypedArray): TypedArray;

crypto.randomUUID(): string;

crypto.subtle.digest(algorithm: string | object, data: ArrayBuffer): Promise<ArrayBuffer>;

crypto.subtle.encrypt(algorithm: object, key: CryptoKey, data: ArrayBuffer): Promise<ArrayBuffer>;

crypto.subtle.decrypt(algorithm: object, key: CryptoKey, data: ArrayBuffer): Promise<ArrayBuffer>;

crypto.subtle.sign(algorithm: string | object, key: CryptoKey, data: ArrayBuffer): Promise<ArrayBuffer>;

crypto.subtle.verify(algorithm: string | object, key: CryptoKey, signature: BufferSource, data: ArrayBuffer): Promise<boolean>;

crypto.subtle.generateKey(algorithm: object, extractable: boolean, keyUsages: Array<string>): Promise<CryptoKey | CryptoKeyPair>;

crypto.subtle.deriveKey(algorithm: object, baseKey: CryptoKey, derivedKeyAlgorithm: object, extractable: boolean, keyUsages: Array<string>): Promise<CryptoKey>;

crypto.subtle.importKey(format: string, keyData: BufferSource, algorithm: string | object, extractable: boolean, keyUsages: Array<string>): Promise<CryptoKey>;

crypto.subtle.exportKey(format: string, key: CryptoKey): Promise<ArrayBuffer>;

crypto.subtle.deriveBits(algorithm: object, baseKey: CryptoKey, length: integer): Promise<ArrayBuffer>;

crypto.subtle.wrapKey(format: string, key: CryptoKey, wrappingKey: CryptoKey, wrapAlgo: string | object): Promise<ArrayBuffer>;;

crypto.subtle.unwrapKey(format: string, wrappedKey: ArrayBuffer, unwrappingKey: CryptoKey, unwrapAlgo: string | object, unwrappedKeyAlgo: string | object, extractable: boolean, keyUsages: Array<string>): Promise<CryptoKey>;

function uint8ArrayToHex(arr) {
    return Array.prototype.map.call(arr, (x) => ((`0${x.toString(16)}`).slice(-2))).join('');
}

async function handleEvent(event) {
    const encodeArr = TextEncoder().encode('hello world');
    // Execute MD5.
    const md5Buffer = await crypto.subtle.digest({ name: 'MD5' }, encodeArr);
    // Generate a hexadecimal string.
    const md5Str = uint8ArrayToHex(new Uint8Array(md5Buffer));

    const response = new Response(md5Str);
    return response;
}

addEventListener('fetch', async (event) => {    
  event.respondWith(handleEvent(event));
});